This is a 2004 forman 450, when I have the bushhog hooked up and pulling along in 1st gear, I will do this for about 10 to 15 minutes and it shuts off. It won't start after it shuts off unless I wait about 15 minutes, no I change the oil and clean the air filter but this sounds like a fuel related issue. I think it might be a bad plug failing under load of the bush hog, I have been doing this for 2 years now and this just started happening. I haven't changed the plug so I'll see if that helps unless I am unaware of a problem with this unit. thanks guys